Addition Shortcuts

Addition of numbers close to multiplies of ten (e.g. 19,29,38,59 etc.)

This technique is useful for Mental calculations

117+49 (Here we can write this 49 as 50-1)
= 117 + (50 - 1)
= 117 + 50 - 1
= 167 - 1 (Instead of adding 49 to 117, we just add 50 to 117 (because we can do this without using pen and paper) and later we subtract one from it)
= 166
Try this.. This is very useful tip while doing calculations.

Now lets try another example.
117+95
= 117 + (100 - 5)
= 117 + 100 - 5 (Here, instead of adding 95 to 117, we are just adding a 100 to 116 and then subtracting from it :)
= 217 - 5
= 212

Addition of decimals 

14.5 + 8.25
= (14 + 0.5) + (8 + 0.25)
= 14 + 8 + 0.5 + 0.25 (Here we just added the rounded numbers first and later we added the decimal numbers :)
= 22 + 0.5 + 0.25
= 22.75